Chevrolet 70 Series 1970, Service Manual

Page: 136 / 841

CAB AND BODY MOUNTINGS 1-105
R efrigerant has very little odor, but in large
concentrations a d istin ct odor may be detected. It
is c o lo r le s s in both its liquid and gaseou s sta te s.
R efrigerant is nonpoisonous, nonflam m able,
and nonexplosive. It is n on corrosive to any of the
ordinary m etals.
G oggles should be worn w henever th ere is the
s lig h te st p o ssib ility of refrigeran t com ing in con­
tact with the fa c e or e y e s, b eca u se refrigeran t
evaporates and co o ls so rapidly it w ill ca u se an
injury sim ila r to fro stb ite.
PROCUREMENT
R efrigerant is gen erally shipped and stored
in 2 5 -lb . drum s and 1 5 -o z. can s.
It w ill be im p o ssib le to draw a ll the r e fr ig e r ­
ant out of the drum. The u se of warm w ater when
charging the sy ste m w ill a ssu r e the extraction of
a m axim um amount of refrigeran t from the drum.
B e su r e to follow the in stru ction s under "Charging
The System " explained la te r .
PRECAUTIONS IN HANDLING REFRIGERANT
1. DO NOT le a v e container of refrigeran t un­
capped.
2. DO NOT subject container to high tem p er­
ature.
3. DO NOT w eld or stea m clean on or near
s y ste m .
4. DO NOT f ill drum (when used) com p letely.
5. DO NOT d isch arge vapor into area w here
flam e is exposed.
6
. DO NOT exp ose e y e s to liquid.
A ll refrig era n t drum s a r e shipped with a
heavy m etal sc r e w cap. The purpose of the cap is
to p ro tect the valve and safety plug from dam age.
It is good p ra ctice to rep la ce the cap after each
u se of the drum fo r the sam e rea so n . If the drum
is exposed to the radiant heat from the sun, the
resultant in c r e a se in p r e s s u r e may ca u se the
sa fety plug to r e le a s e or the drum to burst.
F or the sa m e reason , the refrigeran t container
should never be subjected to e x c e s s iv e tem p er­
ature when charging a sy ste m . The refrigeran t
drum (when used) should be heated fo r charging
p u rp oses by p lacin g in 125°F . w ater. N ever heat
above 1 2 5 °F ., or u se blow torch, radiator, o r stove
to heat the drum.
W elding or ste a m cleaning on or near any of
the r efrig era n t lin e s o r com ponents of the a ir con­
ditioning sy ste m could build up dangerous and
dam aging p r e s s u r e s in the sy ste m .
If a sm a ll drum is ever fille d from a large
one, never f ill the drum com p letely. Space should
alw ays be allow ed above the liquid for expansion.
W eighing drum s b efore and during the tra n sfer
w ill d eterm ine fu lln e ss o f drum s.
D ischarging la r g e quantities of refrigeran t
into a room can usually be done sa fely a s the vapor
would produce no ill e ffe c ts. H owever, th is should
not be done if the area contains a flam e-producing
d evice such a s a g a s h eater. While refrigeran t
n orm ally is nonpoisonous, heavy concentrations
of it in contact with a liv e flam e w ill produce a
poisonous g a s. The sam e g a s w ill attach a ll bright
m etal s u r fa c e s.
PRECAUTIONS
DO NOT EXPO SE E Y E S
TO R EFR IG ER A N T
One of the most important precau­
tions is protection of the eyes when handl­
ing refrigerant. Any liquid refrigerant
which may accidentally escape is approx­
imately 21.7°F., below zero. If any re­
frigerant comes in contact with the eyes,
serious injury could result. Always wear
goggles to protect the eyes when handling
refrigerant.
If refrigerant should come in contact
with the eyes:
1. DO NOT rub the eyes. Splash the eyes
with cold water to gradually get the
temperature above the freezing point.
2. Apply a protective film of an antisep­
tic oil over the eye-ball to reduce the
possibility of infection.
3. Consult a doctor or an eye specialist
immediately.
Should liquid refrigerant come in con­
tact with the skin, the injury should be
treated the same as though the skin had
been frostbitten or frozen.
REFRIGERANT CIRCULATION
R efrigeran t control u n its and piping is illu s ­
trated in fig u res 1 and 2. A com plete cy c le of the
refrig era tin g sy ste m (fig. 3) is a s follow s:
1. R efrigerant in its g a seo u s sta te i s drawn
into the co m p r e sso r w here it is co m p ressed and
d isch arged into the condenser.
2. A s the heated gas c ir c u la te s through the
condenser c o ils , it i s cooled by a ir being forced
through the condenser by an engine cooling fan. The
com bined e ffects of the d ecrea sed tem perature and
in crea sin g p r e s s u r e cause the gas to condense
(liquify).
3. The liquid refrig era n t is then forced from
con d en ser into the liquid r e c e iv e r .
4. B y its own p r e s s u r e , liquid refrigeran t is
fo rced from liquid receiv er-d eh y d ra to r through
the expansion valve and into the evaporator.
5. In the evaporator, w here the p r e s s u r e is
CHEVROLET SERIES 70-90 HEAVY DUTY TRUCK SHOP MANUAL